# Salat times

Salat times at Taipei Cultural Mosque in Taiwan.

Salat times refers to times when Muslims perform prayers (salat). The term is primarily used for the five daily prayers plus the Friday prayer. According to Muslim beliefs, the salat times were taught by Allah to Muhammad.

Prayer times are standard for Muslims in the world, especially the fard prayer times. They depend on the condition of the Sun and geography. There are varying opinions regarding the exact salat times, the schools of Islamic thought differing in minor details. All schools agree that any given prayer cannot be performed before its stipulated time.

## Five daily prayers

The five daily prayers are obligatory (fard) and they are performed at times determined essentially by the position of the Sun in the sky. Hence, salat times vary at different locations on the Earth.

### Fajr (pre-dawn)

Main article: Fajr

Fajr begins at subh saadiq - true dawn or morning twilight when the morning light appears across the full width of the sky and ends at sunrise

### Dhuhr (midday)

Main article: Dhuhr

The Dhuhr prayer starts after the sun passes its zenith, and lasts until Asr

### Asr (afternoon)

Main article: Asr

The Asr prayer starts when the shadow of an object is the same length as the object itself (or, according to Hanafi fiqh, twice its length) and lasts till sunset. Asr can be split into two sections; the preferred time is before the sun starts to turn orange, while the time of necessity is from when the sun turns orange until sunset.

### Maghrib (sunset)

Main article: Maghrib

The Maghrib prayer begins when the sun sets, and lasts till the red light has left the sky in the west.

### Isha'a (night)

Main article: Isha'a

The Isha'a prayer starts when the red light is gone from the western sky, and lasts until the rise of the "white light" (fajar sadiq) in the east. The preferred time for Isha'a is before midnight, meaning halfway between sunset and sunrise.

## Time calculation

Equation of time
Declination of the sun

To calculate prayer times two astronomical measures are necessary, the declination of the sun and the difference between clock time and sundial clock. This difference being the result of the eccentricity of the earth's orbit and the inclination of its axis, it is called the Equation of time. The declination of the sun is the angle between sun's rays and the equator plan.[1]

In addition to the above measures, to calculate prayer times for a specific location we need its spherical coordinates.[2]

In the following $T_Z$ is the time zone, and $T_E$ the time equation value. $L$ and $D$ are respectively the Longitude and the Latitude of the considered point.

An other important equation gives the time difference between when the sun hits its highest point in the sky (Dhuhr time) and any other angle $\alpha$, as follow: $T(\alpha) = {1 \over 15} \arccos \left( {-\sin(\alpha)-\sin(L)*\sin(D) \over \cos(L)*\cos(D)} \right)$

• Midday (Dhuhr) time is easily obtained. When the sun reaches the mid sky, time is given by: $T_{Dhuhr} = 12 + T_Z - (L/15 + T_E)$
• Sunrise (Chorok) and Sunset (Maghreb) time are given by $T(0.833)$, in fact it is the astronomical sunset/sunrise that occurs for $\alpha = 0$. 0.833 is a slight correction that gives the actual time. So $T_{Chorok} = T_{Dhuhr} - T(0.833)$ and $T_{Sunset} = T_{Dhuhr} + T(0.833)$.

If we consider the elevation of the point we should add another correction to the constant $0.0347 \times \sqrt{h}$.

• For Fajr and Isha many conventions about the angle $\alpha$ exist. It is of 17 and 18 degrees respectively for Fadjr and Isha prayers according to the Muslim World League.
• For Asr time according to the majority of Muslim schools, including Shafi'i, Maliki, Ja'fari, and Hanbali, it is when the length of an object shadows became equal to its length plus the length of its shadow at noon. The Hanafi schools states that the time of Asr is when an object's shadow reaches two times the length of the object itself, plus the length of its shadow at noon. The time the shadow of an object reaches $T$ times its length is given by the equation: $A(T) = {1 \over 15} \arccos \left( {\sin(\arccot(t+\tan(L-D)))-\sin(L)*\sin(D) \over \cos(L)*\cos(D)} \right)$.
• It is called for the Maghrib prayer when the sun is completely folded behind the horizon, plus 3 minutes by precaution.

## Friday prayer

Main article: Jumu'ah

The Friday prayer replaces the dhuhr prayer performed on the other six days of the week. The precise time for this congregational prayer varies with the mosque, but in all cases it must be performed after the dhuhr and before the asr times. If one is unable to join the congregation, then they must pray the dhuhr prayer instead. This salat is compulsory to be done with ja'maat for men. Women have the option to perform Jumm'ah in the mosque or to pray dhuhr